SpringCloud 学习记录(一)：服务注册与发现(eureka+feign)

前面介绍过dubbo远程接口调用的简单使用，这里我们将开始学习如何使用springcloud微服务架构中的服务注册与发现。

一，eureka-server

eureka分为服务端和客户端两部分， eureka server是一个服务注册中心，类似于zookeeper，当然，也可以使用zookeeper代替，后面会详细说明。

首先，新建一个maven springboot应用，这里命名为eureka-server

1，添加依赖包

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka-server</artifactId></dependency>

2，添加配置文件application.properties

#应用名称spring.application.name=eureka-server#服务端口server.port=8080#实例ip地址eureka.instance.hostname=localhost#设置当前的eureka服务禁止被当做客户端注册eureka.client.register-with-eureka=falseeureka.client.fetch-registry=false#设置服务发现地址eureka.client.serviceUrl.defaultZone=http://localhost:${server.port}/eureka/

3，启动类Application.java添加注解@EnableEurekaServer

package com.example;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.builder.SpringApplicationBuilder;import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;@EnableEurekaServer@SpringBootApplicationpublic class Application {public static void main(String[] args) {new SpringApplicationBuilder(Application.class).web(true).run(args);}}

4，启动访问，此时还没有任何服务注册

二，eureka-client

还是新建一个maven springboot应用，这里命名为eureka-client

1，添加依赖包

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>

2，添加application.properties配置

spring.application.name=eureka-clientserver.port=8081eureka.client.serviceUrl.defaultZone=http://localhost:8080/eureka

3，启动类Application.java添加注解注册服务@EnableDiscoveryClient

package com.example;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.builder.SpringApplicationBuilder;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@EnableDiscoveryClient@SpringBootApplicationpublic class Application {public static void main(String[] args) {new SpringApplicationBuilder(Application.class).web(true).run(args);}}

4，启动后刷新eureka-server界面，会发现多了一个注册的客户端实例eureka-client

三，feign

上面简单演示了使用eureka发现和注册服务，下面我们来看，如何使用feign来实现远程接口的调用。

还是新建一个maven springboot应用，这里命名为eureka-feign

1，添加依赖包

<dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-starter-feign</artifactId></dependency><dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-web</artifactId></dependency>

2，添加配置application.properties

spring.application.name=eureka-feignserver.port=8082eureka.client.serviceUrl.defaultZone=http://localhost:8080/eurekafeign.httpclient.enabled=truefeign.compression.request.enabled=truefeign.compression.request.mime-types=application/jsonfeign.compression.request.min-request-size=2048feign.compression.response.enabled=true

3，Application.java启动类开启注解@EnableFeignClients

package com.example;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.builder.SpringApplicationBuilder;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;import org.springframework.cloud.netflix.feign.EnableFeignClients;import org.springframework.context.annotation.Bean;import feign.Request;@EnableFeignClients@EnableDiscoveryClient@SpringBootApplicationpublic class Application {public static void main(String[] args) {new SpringApplicationBuilder(Application.class).web(true).run(args);}/** * 自定义feign连接超时时间 * @return */@Bean    Request.Options feignOptions() {        return new Request.Options(/**connectTimeoutMillis**/1000 * 1000, /** readTimeoutMillis **/1000 * 1000);    }}

4，启动，刷新eureka-server界面，可以看到服务已经注册成功

5，添加测试类，从eureka-feign服务中调用eureka-client中的接口

(1) 在eureka-feign中添加TestController.java

package com.example;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class TestController {    @Autowired    TestClient testClient;        @RequestMapping(value="/test",method=RequestMethod.GET)    public String test() {    String msg = testClient.test();    return msg;    }}

(2) 定义接口TestClient.java，指定实现服务的@FeignClient("eureka-client")

package com.example;import org.springframework.cloud.netflix.feign.FeignClient;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;@FeignClient("eureka-client")public interface TestClient {    @RequestMapping(value="/test",method=RequestMethod.GET)    String test();}

(3) 在eureka-client中添加接口实现

package com.example;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class TestController {    @RequestMapping(value="/test",method=RequestMethod.GET)    public String test() {        String msg = "this service is eureka-client";        return msg;    }}

注意：feign接口调用使用的仍然是http协议，且支持spring注解，参数需与调用方一致。

接下来启动服务，访问http://localhost:8082/test，查看测试结果：

6，feign还支持负载均衡，不需要额外配置，继续保存服务开启状态，修改eureka-client的port=8083，然后启动

此时有两个eureka-client实例提供服务：

再次访问http://localhost:8082/test，这里共测试了4次，查看控制台日志，端口为8081和端口为8083的服务各调用了两次。

8081端口日志：

2017-08-09 16:50:24.671  INFO 3104 --- [           main] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1502268624671, current=UP, previous=STARTING]2017-08-09 16:50:24.674  INFO 3104 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_EUREKA-CLIENT/PC-201611261236:eureka-client:8081: registering service...2017-08-09 16:50:24.739  INFO 3104 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_EUREKA-CLIENT/PC-201611261236:eureka-client:8081 - registration status: 2042017-08-09 16:50:24.823  INFO 3104 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8081 (http)2017-08-09 16:50:24.825  INFO 3104 --- [           main] .s.c.n.e.s.EurekaAutoServiceRegistration : Updating port to 80812017-08-09 16:50:24.830  INFO 3104 --- [           main] com.example.Application                  : Started Application in 8.949 seconds (JVM running for 9.584)2017-08-09 16:53:24.596  INFO 3104 --- [nio-8081-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'2017-08-09 16:53:24.598  INFO 3104 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started2017-08-09 16:53:24.634  INFO 3104 --- [nio-8081-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 36 ms--------------this service is eureka-client--------------this service is eureka-client2017-08-09 16:55:24.319  INFO 3104 --- [trap-executor-0] c.n.d.s.r.aws.ConfigClusterResolver      : Resolving eureka endpoints via configuration

8083端口日志：

2017-08-09 16:54:02.333  INFO 4640 --- [           main] com.netflix.discovery.DiscoveryClient    : Saw local status change event StatusChangeEvent [timestamp=1502268842333, current=UP, previous=STARTING]2017-08-09 16:54:02.336  INFO 4640 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_EUREKA-CLIENT/PC-201611261236:eureka-client:8083: registering service...2017-08-09 16:54:02.413  INFO 4640 --- [nfoReplicator-0] com.netflix.discovery.DiscoveryClient    : DiscoveryClient_EUREKA-CLIENT/PC-201611261236:eureka-client:8083 - registration status: 2042017-08-09 16:54:02.466  INFO 4640 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8083 (http)2017-08-09 16:54:02.467  INFO 4640 --- [           main] .s.c.n.e.s.EurekaAutoServiceRegistration : Updating port to 80832017-08-09 16:54:02.477  INFO 4640 --- [           main] com.example.Application                  : Started Application in 8.863 seconds (JVM running for 9.467)2017-08-09 16:54:05.998  INFO 4640 --- [nio-8083-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'2017-08-09 16:54:05.999  INFO 4640 --- [nio-8083-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started2017-08-09 16:54:06.027  INFO 4640 --- [nio-8083-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 28 ms--------------this service is eureka-client--------------this service is eureka-client2017-08-09 16:59:01.991  INFO 4640 --- [trap-executor-0] c.n.d.s.r.aws.ConfigClusterResolver      : Resolving eureka endpoints via configuration

四，上面我们提到过，服务注册不一定要用eureka，下面我们使用zookeeper来代替使用。

首先，对eureka-feign和eureka-client进行改造，主要是配置修改。

1，修改依赖包，将eureka包注释掉，添加zookeeper依赖

<!--         <dependency> --><!--             <groupId>org.springframework.cloud</groupId> --><!--             <artifactId>spring-cloud-starter-eureka</artifactId> --><!--         </dependency> -->        <dependency>            <groupId>org.springframework.cloud</groupId>            <artifactId>spring-cloud-starter-zookeeper-all</artifactId>        </dependency>

2，将application.properties中的eureka服务地址注释掉

#eureka.client.serviceUrl.defaultZone=http://localhost:8080/eureka

3，添加bootstrap.properties，指定zookeeper地址

spring.cloud.zookeeper.connectString=localhost:2181spring.cloud.zookeeper.discovery.instancePort=${server.port}

4，其他配置都不变，开启zookeeper，然后同时开启eureka-feign和eureka-client

访问http://localhost:8082/test，同样可以得到相同的测试结果：